Having tested both Realms and KMongo i can say that the MongoDB Kotlin driver is lacking a lot when it comes to idiomatic kotlin.

First of all, requiring Strings and not accepting KProperty<T> forcing people to type Foo::bar.name is something that should have never made past v1.0
Second of all, the kotlin driver doesnt solve any of the issues that KMongo had - in fact, its a downgrade from KMongo. Update doesnt accept Kotin objects as a parameter something that is done by Realms.

In order for MongoDB Kotlin driver to even be considered usable it needs to be better than its community alternative.